Aims:Candida albicans remains the most common species causing human infections but recent epidemiological data reveal shift from C. albicans to non C. albicans species. The aim of our study is to detect the clinical distribution of Candida species in a tertiary hospital.Materials and Methods: Fifty Candida isolates from clinical samples were studied. The samples were inoculated on Sabouraud's Dextrose Agar (SDA) and Hichrom agar and incubated at 37°C. Growth on SDA were identified and speciated by standard methods. Candida species were identified on Hichrom agar by morphology and color of the colony and were compared with conventional methods. Anti-fungal susceptibility was performed by disc diffusion method using commercially available anti-fungal discs (HiMedia).Results: Out of 50 Candida isolates collected 62% were from males and 38% from females. The distribution of the clinical samples was urine 44%, exudate 32%, respiratory 14% and blood 10%. C. albicans (54%) was the most common species isolated from these samples. The distribution of non C. albicans were C. tropicalis (18%), -C. krusei (12%), - C. glabrata (10%),- C. rugosa (6%). Among the non-albicans C. tropicalis was seen predominantly in urine and exudates. The specificity and sensitivity of Hichrom agar was 98%. Antibiotic susceptibility pattern shows that about 38% of C. albicans and 17% C. krusei isolates were resistant to fluconazole. Conclusions: Percentage of non-albicans species (46%) are increased in the prevalence with C. albicans (54%) as the predominant species from clinical samples. Anti-fungal profile shows an increased percentage of resistance to fluconazole.

Keywords: Anti-fungal susceptibility, Candida species, hichrom agar

How to cite this article:Sukumaran J, Sundaram JM, Sivan RR. Changing trend in the clinical distribution of Candida species in a tertiary care hospital. J NTR Univ Health Sci 2012;1:222-6

Yeasts were always identified as etiological agents of human infections. Candida often regarded as contaminant in laboratories has emerged as potentially aggressive pathogen today. The rise of systemic Candida infections are related with several factors like immunocompromised status-HIV/excessive use of broad spectrum antibiotics and metabolic disorders. [1] Although C. albicans remains the most common species, there has been an increase in the number of infections caused by non C.albicans species such as C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei. Recent epidemiological data reveal shift from C. albicans to non C. albicans species. Besides epidemiological pattern change, there is an increase of Candida species resistant to conventional therapy. [2] Therefore, rapid and correct identification of Candida species is fundamental in ensuring specific, early and effective antifungal therapy. Chromogenic media (HiMedia) is used for rapid yeast identification. This media contains chromogenic substrates that react with enzymes secreted by micro-organisms producing colonies with various pigmentation. These enzymes are species specific, allowing organisms to be identified to the species level by their Color and colony characteristics. [3] This study was carried out to detect the clinical distribution of the Candida species and to compare conventional method and use of Chromogenic media for rapid identification of Candida species.

Materials and Methods

A total of 50 Candida isolates from different clinical samples of patients who attended outpatient and inpatient departments of a tertiary care hospital during the period June to December, 2011were studied. Direct Gram staining was carried out with the sample. They were inoculated on Sabouraud's Dextrose Media and incubated at 25°C and 37°C. Growth on SDA were identified by standard methods such as gram staining, germ tube formation, chlamydospore formation on corn meal agar, and sugar fermentation and assimilation tests. Candida isolates were also inoculated onto Hichrom agar and incubated at 37°C for 48 hours. Species were identified on Hichrom agar (HiMedia) by morphology and color of the colony. The color of various species of Candida on HiChrom agar are as follows.

Out of 50 Candida isolates studied 62% were from males and 38% were from females. The distribution of the clinical samples were urine 22 (44%), exudate 16(32%), respiratory 7(14%) and blood 5(10%). C. albicans (54%) was the most common species isolated from these samples. The distribution of non C. albicans were C. tropicalis (18%, 9/50), C. krusei (12%, 6/50), C. glabrata (10%, 5/50), C. rugosa (6%, 3/50) as shown in the [Table 1].

Candida isolates were 100% sensitive to amphotericin B, nystatin, ketoconazole and itraconazole. Among the 27 C. albicans, 10 (38%) were resistant to fluconazole. Out of 6 C. krusei 4 strains were resistant to fluconazole.

Discussion

There has been a surge of infections due to yeast other than C. albicans because of the increasing complexity in the management and disease profiles of patients. Over the past decade, there has been a significant increase in the number of reports of systemic and mucosal yeast infections with Candida species other than C. albicans. [4] The potential clinical importance of species level identification guides early appropriate antifungal therapy. In people who have a weakened immune system because of cancer treatments,steroids, or diseases such as AIDS, systemic Candida infections can occur and can be life threatening. So studying the prevalence of infections by Candida becomes important.

The present study shows C. albicans as the predominant isolate from the different clinical samples similar to the studies by Mujika et.al, 2004. [5] Non albicans Candida was reported at a higher rate in the above study. The predominance (54%) of C. albicans in this study correlates to the studies reported by Kao AS et al. and Sengupta P, Ohri VC. [6],[7] In studies done by Agarwal et al. 2011 and Prasad et al. 1999 [8],[9] They had reported that C. albicans was the predominant (47.6%) pathogenic species isolated from various clinical specimens.

Among the 23 (46%) non- albicans, C. tropicalis (18%) was the predominant organism isolated in this study. Studies done by SomansuBasu and Harish C et al. 2003 [10] recovered C. tropicalis in a similar frequency followed by C. krusei and C. glabrata.

In the present study, Candida albicans were predominantly isolated from urine samples (41%) followed by exudates (18%), respiratory (8%), and blood (6%). Many reports show the increased incidence of Candida infection in the genitourinary tract in all areas of medical and surgical practice. Kidney is often the earliest target organ involved in hematogenous Candida infections. Candidal colonization of the urinary tract is common in patients with diabetes, patients receiving broad-spectrum antibiotics or immunosuppressants, or those with long-term urinary catheters. [10] Our study correlated with the previous studies, [7],[8] in that among the clinical samples more number of Candida isolates were found in urine sample (44%). C. albicans was predominant in urine samples followed by C. krusei and C. tropicalis.

Candida is a normal inhabitant of the mouth and can be recovered from sputum in 20 to 55% of normal subjects. [11] The prevalence and prognosis of pulmonary Candidal infection has been difficult to evaluate since diagnosis were seldom confirmed, Candida isolated from sputum sample is mostly a colonizer of the respiratory tract. The role of Candida in pulmonary Candidiasis and its diagnosis is still controversial. The isolation of Candida species from respiratory specimens is frequent in mechanically ventilated patients. Among 50 isolates, 7 (14%) were from respiratory samples.

Candida species account for 8-15% nosocomial blood stream infections and forms the fourth common isolate of patients in intensive care unit. From PGI Chandigarh an Eleven- fold increase in Candidemia was reported. [11] We received 5 isolates from blood samples, in that C. albicans and C. tropicalis were reported. In India also there is rise in frequency of non-albicans as reported by several authors. [9],[10] They were isolated from several tertiary care centers in India, isolation rate ranging from 52%-96%. Out of 5 isolates 3 (60%) were non-albicans and 2 (40%) C. albicans.

Candida without pseudohyphae could be successfully identified only through automated systems like the V2C system, PCR-based restriction endonuclease analysis (PCR-REA) and multiplex real-time PCR with molecular beacons MBs. None of these methods were self-sufficient in identifying all Candida species in all clinical specimens. [12] Thus, a judicious and cost-effective workflow needs to be applied for routine identification of such isolates in clinical laboratories. The HiChrom agar for Candida can be used as culture medium for the primary isolation and presumptive identification of organisms in cases where early diagnosis of infections is needed without doing PCR. [13] In our study, we compared the isolation rates of Candida species using both HiChrom agar and conventional methods. In our study, we also found that using HiChrom agar several species of Candida can be easily identified on the basis of colony colour and morphology and accurately differentiates between the three most common species of Candida, i.e. C. albicans, C. tropicalis, and C. krusei, which has also been reported by Lynn et al. [3]

The specificity and sensitivity of HiChrom agar for Candida species for green colour colony of C. albicans was calculated as 100%, for blue colonies with dark center surrounded by gray halo of C. tropicalis calculated as 98%, and for pink rough and spreading colonies with broad white edges of C. krusei as 100%. Antifungal susceptibility pattern shows that about 38% of C. albicans isolates are resistant to fluconazole. Among the non albicans, (17%) strains are resistant to fluconazole correlated with the studies. [14],[15]

Conclusion

The present study shows C. albicans as the predominant species in different clinical samples. Percentage of non-albicans species are also on the increase in the prevalence. Antifungal profile shows an increased percentage of resistance observed among C. albicans to fluconazole. This necessitates the importance of antifungal profile before starting therapy for these infections.

The present study found that use of HiChrom agar medium would enable the laboratories to rapidly identify and speciate the clinically important Candida species while potentially reducing the patient's morbidity and mortality.

Kao AS, Brandt ME, Pruit WR, Conn LA, Perkins BA, Stephens DS, et al. The epidemiology of candidemia in two United States cities: Result of a population based active surveillance.Clin Infect Dis 1999;29:1164-70.